It is known in existing commercial mixers to provide multiple speed settings for the mixers. The various available mixing speeds are primarily driven by a motor through combinations of gears and/or belts and/or variable adjustable pulleys, where mechanical adjustments are made to change mix speeds. Many such devices require that the mixer be stopped in order to change speeds.
U.S. Pat. No. 5,934,802 is representative of a mixer that did not utilize mechanical adjustment of any drive linkage or gear system to change speeds, but instead simply adjusted the output speed of a DC motor. However, control of the DC motor was implemented in a relatively simple manner, using a potentiometric speed control switch to adjust a PWM signal delivered to the motor. No feedback of motor speed was provided. In larger commercial mixers, use of a DC motor is impractical due to the size of the DC motor needed to provide sufficient torque.
Accordingly, it would be advantageous to provide a mixer that can change speeds on the fly and provide sufficient torque for commercial mixing applications.